The Isotopic Mixture of Magnesium in 47 Tucanae

Wednesday, 17 April 2013 9 a.m. — 10 a.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
ANDERS THYGESEN (Heidelberg University and Gemini South Visiting Astronomer)

By now it is well-known that most (if not all) globular clusters harbour at least two generations of stars. This fact is observed in, for instance, anticorrelations of [Na/Fe]-[O/Fe] and [Mg/Fe]-[Al/Fe]. These correlations are believed to be caused by self-enrichment from an earlier generation of stars. However, the nature of these first-generation polluters is still a matter of debate, being AGB stars, Very Massive Fast Rotators or something else entirely. In cases where isotopic mixtures can be measured, additional constraints can be put on the first generation cluster stars and on the nucleosynthesis history of the cluster. Here we present results on Mg-isotopic ratios in giant stars in the metal-rich globular cluster 47 Tucanae. This is the most metal-rich cluster in which such an analysis has been performed to date and will provide an important test of nucleosynthesis in a high-metallicity environment.